Process for the preparation of trans-polypentenamers

ABSTRACT

METHOD FOR PRODUCING TRANS-POLYPENTENAMER FROM CYCLOPENTENE BY MEANS OF A CATALYST COMPRISING: (A) A TUNGSTEN SALT (B) AN ORGANIC EPOXIDE (C) AN ORGANO-ALUMINIUM COMPOUND.

United States Patent Olfice 3,632,849 Patented Jan. 4, 1972 3,632,849 PROCESS FOR THE PREPARATION OF TRANS- POLYPENTENAMERS Gottfried Pampus, Leverkusen, and Josef Witte, Cologne- Starnmheim, Germany, assignors to Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany N Drawing. Filed Mar. 19, 1969, Ser. No. 808,693 Claims priority, application Germany, Apr. 6, 1968,

P 17 70 143.8 Int. Cl. C08f 7/02 US. Cl. 260-931 Claims ABSTRACT OF THE DHSCLOSURE Method for producing trans-polypentenamer from cyclopentene by means of a catalyst comprising:

(a) A tungsten salt (b) An organic epoxide (c) An organo-aluminium compound.

The polymerisation of cyclopentenes using organometallic mixed catalysts based on organic aluminium compounds and tungsten salts is known. This polymerisation results in ring opening and the formation of linear unsaturated hydrocarbons in which the carbon-carbon double bonds are substantially in the trans configuration. A process for bulk polymerisation of cyclopentene with ring opening and trans-polypentenamer formation is described in British patent specification 1,010,860. This process has, however, serious disadvantages which make it difiicult to carry it out on a technical scale. Bulk polymerisation produces reaction mixtures which are so viscous that it is impossible to control the temperature during the polymerisation. Furthermore, polymerisation can only be carried out to a conversion, of to 50 percent, if a polymer which is not cross-linked and which can be worked up is to be obtained. At higher conversion insoluble crosslinked products which are of no technical interest are obtained. Moreover, as will be seen from the examples in British patent specification 1,010,860, very high quantities of catalysts are used, and long reaction times are required.

British patent specification 1,062,367 describes a process for the preparation of polyalkenamers in which the catalysts used are, inter alia, mixtures of a tungsten salt (e.g. WCl a compound which contains an oxygen-oxygen bond or an oxygen-hydrogen bond, and an organic aluminium compound. This process is preferably carried out in the absence of inert diluents, and temperature control therefore becomes impossible owing to the extremely high viscosities of the reaction mixture. In this process, only moderate yields of to were obtained with relatively high catalyst concentrations although in shorter reaction times.

Furthermore, in these processes considerable technical difficulties are involved in short stopping the polymerisation owing to the high viscosity of the reaction mixture. The removal of the catalyst residues and the uniform distribution of the stabiliser in the polymer are verydifiicult when the process is carried out on a large industrial scale. If the processes described in the above-mentionad patents are carried out in the presence of inert solvents, e.g. aliphatic or aromatic hydrocarbons, the conversion of cyclopentene to polypentenamers is even less so that the process becomes technically useless.

It is an object of this invention to provide an improved process for producing polypentenamer. Another object is a catalyst for carrying out this process.

A process for the preparation of trans-polypentenamers has now been found in which a solution of cyclopentene in inert aliphatic, cycloaliphatic or aromatic hydrocarbons is contacted with an organometallic mixed catalyst of (a) a tungsten salt, (b) an epoxide and (c) an organic aluminium compound the molar ratio of a:b:c being 1:03 to 10:0.8-l5.

Suitable solvent for use in the process of the invention are aliphatic hydrocarbons such as butane, pentane, hexane, iso-octane or cycloaliphatic compounds such as cyclohexane or aromatic compounds such as benzene, toluene or xylene. 5 to 50% solutions of cyclopentene in these solvents may be used for the process. Monomer concentrations of 10 to 30% are preferably employed.

The following are examples of compounds which may be used as catalyst components:

(a) WCl WBr WCl O; (b) Epoxides of the general formula X is a hydrogen atom, or an alkyl, aryl or aralkyl group,

Y is a hydrogen atom, an alkyl, aryl or aralkyl group, or a group of the formula -CH I-Ial (Hal Cl, Br, I) -CH -OR (R is an alkyl or aryl group) H,

X and Y may be substituted, e.g. by alkyl groups (methyl) or halogen atoms (chlorine).

With reference to X and Y alkyl is preferably alkyl having 1-6 carbon atoms. Aryl is preferably phenyl, naphthyl, biphenyl. Aralkyl is preferably benzyl.

Preferred epoxides are lower alkylene epoxides as ethylene oxide, propylene oxide, butylene oxide and epichlorohydroxine as well as phenoxy-propylene oxide.

(0) Aluminium trialkyl, e.g. (Al(C H Al(C H Al(iso-C H aluminium halogen alkyl, e.g.

Al C H C1 Al(C H Br, Al(C H )Cl and aluminium alkoxyalkyls, e.g. Al(C2H5)2OC2H5.

The catalyst components may be used in the following molar ratios: a:b:c=1:0.3 to 1020.8 to 15. The amount of catalyst used is 0.1 to 4 mmol, preferably 0.3 to 2 mmol of tungsten salt per 100 g. of monomer.

In a preferred method for carrying out the process, the tungsten salt is first added to the monomer solution, followed by the epoxide and lastly by the organic aluminium compound.

The temperature during the preparation of the catalyst may be between and +60 C. and is preferably between -20 and +20 C.

Polymerisation starts immediately on addition of the organic aluminium compound. The polymerisation temperature may be between -60 and +60 0, preferably between -20 and +30 C. The polymerisation time is 1 to 5 hours. Conversions of cyclopentene to the transpolypentenamer of to and more are then obtained. No gel formation occurs even at such high conversion rates.

The molecular weight of the polymers can be adjusted by suitable choice of the catalyst composition (ratio of the components) and of the sequence in which the components are added.

When the desired degree of conversion has been achieved, polymerisation is stopped by the addition of alcohols, carboxylic acids and/ or amines. One of the usual products, e.g. phenyl-fi-naphthylamine, 2,6-di-tertiarybutyl-4-methyl phenol or 2,2'-di-hydroxy-3,3'-di-tertiarybutyl-5,5-dirnethyl-diphenylmethane is added to the polymer solution as stabiliser and age resistor in quantities of 0.23%.

The polymer can be isolated by precipitation with an alcohol such as methanol, ethanol or isopropanel. On a technical scale, the polymer solution is preferably worked 3 up by introducing it into hot water, unreacted monomer and an azeotropic mixture of the solvent and water distilling 011 in the process. The polymer is precipitated in the Water as a crumb suspension and is separated from the water and dried either in a drying oven or on a platform drier or in a screw extruder.

The trans-polypentenamer is a rubbery polymer. It can be cross-linked using known vulcanisation systems and worked up on rubber processing machines.

EXAMPLE 1 800 g. of anhydrous benzene are introduced under a nitrogen atmosphere into a vessel equipped with a mechanical stirrer. 200 g. of cyclopentene and 1.58 g. (4 mmol) of tungsten hexachloride are then added at room temperature (23 C.) with the exclusion of oxygen and moisture. This solution of monomer and W01 is cooled to --l C., and 0.37 g. (4 mmol) of epichlorohydrin and 0.992 g. mmol) of aluminium triisobutyl are then added with stirring and with the exclusion of oxygen and moisture. Polymerisation starts immediately on addition of the organic aluminum compound, as can be seen by the marked increase in the viscosity of the solution. The reaction temperature is controlled by suitable external cooling so that it slowly rises to 0 C. in the course of 4 hours. A solution of 1 g. of 2,2'-dihydroxy-3,3'-ditertiarybutyl-S,5'dimethyl-diphenylmethane, 3 g. of ethanolamine and g. of ethanol in 100 ml. of benzene is then added and the reaction mixture is stirred for 15 minutes. When the reaction in the polymerisation has been stopped and the solution stabilised, the product is precipitated with 3 litres of ethanol. The polymer is dried in vacuo at C.

4 EXAMPLES 9 TO 13 The following examples were carried out as described in Example 1. The proportion of aluminium trialkyl to tungsten hexachloride was varied.

ure, Polymerisation time,

hours 4 4 4 4 4 Yield percent 68 68 73 (7,) toluene, 25 2. 7 2. 0 2.11 1.87 1.78 Percent trans double bond 92. 2 94. 8 94. 8 94. 6 93. 8

1 1.58 grams=4 mmol. 2 0.37 grams=4 mmol.

EXAMPLES 14 TO 20 The tungsten hexachloride is dissolved in 300 ml. of anhydrous toluene, and g. of cyclopentene are then added. The substance which is to be tested as the co-catalyst is then added, the mixture is cooled to 5" C., and the aluminium alkyl compound is added. After 4 hours polymerisation at 5 C., the reaction is stopped with a soluton of 0.5 g. of 2,2'-di-hydroxy-3,3'-di-tertiary-butyl 5,5dimethyldiphenylmethane and 2 g. of N-methyl-diethanolamine, and the polymer is precipitated with ethanol and dried in vacuo at 70 C.

The yield is g., i.e. 77.5% of the theoretical.

7)toluene, 25 0. 94% of the double bonds have a trans-configuration as determined by the IR spectrum.

1 'E trans Calculation: Percent trans= The double bond content, determined by titration with 55 n/ 10 ICl solution corresponds exactly to the theoretical amount.

EXAMPLES 2 TO 8 (COMPARISON TESTS) The following comparison tests corresponding to the prior art were carried out as described in Example 1: 60

Examples 17, 18 and 20 show the distinct superiority of the co-catalysts according to the invention, of the epoxides over open and cyclic ethers (Examples 15 and 16) and over the prior art (Examples 14 and 19).

EXAMPLES 21 TO 24 The following examples were carried out as described in Example 1. The tungsten hexachloride/epoxide ratio was varied.

Example Number Benzene, grams VCvyclopentene, grams.

grams C HEOH, grams Al(iso-C4Hn) grams 0.992 0.992 0.992 0.992 0.99

ure, 10-0 10-0 10-0 10-0 10-0 Polymerisation time Yield, percent 7 45 8 26 5 (1;) (25 0., toluene) 6.0

Example Number Benzene, grams 800 800 800 800 Cyclopentene, grams. 200 200 200 200 Cooled to, C -5 5 -5 -5 E piehlorohydrin:

(Grams) 37 0. 44 0. 0. 55

Polymerisation temperature, C 5+5 5-+5 -5-+5 -5+5 Polymerisation time (hours) 4 4 4 4 Yield, percent 78 76 72 75 n (in toluene at 25 C.) 2. 25 1. 95 1. 81 1. 6

Percent trans double bond- 95. 6 94 94 93. 9

l 1.58 grams=4 mmol.

EXAMPLES 25 TO 27 The following examples were carried out as described in Example 1. The total catalyst concentration was varied.

Example Number Benzene, grams 800 800 800 Cyclopentene, grams 200 200 200 WCls:

(Grams) 1. 58 1.18 0.79 (Mmol). 4 3 2 Cooled to, 0-. 5 --5 -5 E piehlorohydrin:

(Grams) 0. 37 0.28 0. 185 (Mmol) 4 3 2 Al(i-C4He) a.

(Grams) 1. 07 0.89 0. 65 Mmol 5. 4 4. 5 3. 8 Polymerisation temperature, 5+5 5+5 -5+-5 Polymerisation time (hours)..- 4 4 4 Yield, percent 76 79 83 n (in toluene at 25 C.) 1. 83 1. 48 1.02 Percent trans double bonds 93.7 94. 0 93. 7

EXAMPLES 28 TO 34 Monomer solutions were prepared in each case from 500 ml. of anhydrous benzene and 100 g. of anhydrous cyclopentene under a nitrogen atmosphere, using vessels equipped with stirrers. The cyclopentene was contaminated with the following substances: 0.06% of cis-pentadiene 1,3; 0.24% of trans-pentadiene-l,3; 0.6% of 2- methylbutene-2; and 0.035% of isoprene.

1 millimol of WCl was added to each of the monomer solutions at 0 C. and the reaction mixture was in each case stirred for minutes to ensure complete solution. The cocatalyst was then added and the solution cooled to -5 C. The aluminium alkyl compound was then added. Rolymerisation sets in at once, as can be seen by a rapid increase in the viscosity.

The polymerisations, which were carried out at temperatures between --5 and 0 C., were stopped after 4 hours by the addition of 0.5 g. of 2,2-di-hydroxy-3,3'-ditertiary-butyl-S,5-dirnethyl-diphenylmethane and 2 g. of N-methyl-diethanolamine dissolved in 30 ml. of ethanol. The polymers were precipitated with ethanol, kneaded for a short time and dried in vacuo at 60 C. The results of the polymerisation experiments are summarised in the following table.

What is claimed is:

1. A process for producing trans-polypentenamers which comprises dissolving cyclopentene in an inert hydrocarbon solvent and contacting resulting solution with a catalytic amount of a catalyst comprising (a) tungsten hexachloride, tungsten pentabromide or tungsten oxytetrachloride, (b) an epoxide of the formula wherein X is hydrogen, alkyl having 1 to 6 carbon atoms, chloroalkyl having 1 to 6 carbon atoms, phenyl, chlorophenyl, methylphenyl, naphthyl, chloronaphthyl, methylnaphthyl, biphenyl, chlorobiphenyl, methylbiphenyl, benzyl, chlorobenzyl or methylbenzyl and Y is hydrogen, alkyl having 1 to 6 carbon atoms, halomethyl wherein halo is chlorine, bromine or iodine, phenyl, chlorophenyl, methylphenyl, naphthyl, chloronaphthyl, methylnaphthyl, biphenyl, chlorobiphenyl, methylbiphenyl, benzyl, chlorobenzyl or methylbenzyl and (0) aluminum trialkyl, aluminum halogen alkyl or aluminum alkoxyalkyl, the molar ratio of a:b:c being 1:03 to 1020.8 to 15.

2. The process of claim 1 wherein (a) is tungsten hexachloride.

3. The process of claim 1 wherein X and Y are hydrogen or alkyl having 1 to 6 carbon atoms.

4. The process of claim 1 wherein (c) is aluminum trialkyl.

5. The process of claim 1 wherein the temperature is from 60 to 60 C.

6. The process of claim 1 wherein said hydrocarbon solvent is an aliphatic, cycloaliphatic or aromatic hydrocarbon.

7. A catalyst for producing trans-cyclopentenamer comprising (a) tungsten hexachloride, tungsten pentabromide or tungsten oxytetrachloride, (b) an epoxide of the formula wherein X is hydrogen, alkyl having 1 to 6 carbon atoms. chloroalkyl having 1 to 6 carbon atoms, phenyl, chlorophenyl, methylphenyl, naphthyl, chloronaphthyl, methylnaphthyl, biphenyl, chlorobiphenyl, methylbiphenyl, benzyl, chlorobenzyl or methylbenzyl and Y is hydrogen, alkyl having 1 to 6 carbon atoms, halomethyl wherein halo is chlorine, bromine or iodine, phenyl, chlorophenyl, methylphenyl, naphthyl, chloronaphthyl, methylnaphthyl, biphenyl, chlorobiphenyl, methylbiphenyl, benzyl, chlorobenzyl or methylbenzyl and (c) aluminum trialkyl, aluminum halogen alkyl or aluminum alkoxyalkyl, the molar ratio of 1111220 being 120.3 to 10:08 to 15.

8. The catalyst of claim 7 wherein (a) is tungsten hexachloride.

9. The catalyst of claim 7 wherein X and Y are hydrogen or alkyl having 1 to 6 carbon atoms.

10. The catalyst of claim 7 wherein (c) is aluminum trialkyl.

(References on following page) 7 8 References Cited JOSEPH L. SCHOFER, Primary Examiner UNITED STATES PATENTS R. A. GAITHER, Assistant Examiner 3,129,208 4/1964 Jezl et a1. 26093.7 CL 1 3,476,728 11/1969 Natta et a1 260-931 5 3,449,310 6/1969 Dall Asta et a1 260--93.1 252431 3,476,730 11/ 1969 Streek et a1. 260-931 

